Plasma cutting of steel plate in preparation for welded fabrication of multi-sided steel monopoles 4

[VoyageofDiscovery]

I have posted this in Transmission Structure Engineering, with no luck, so forgive me for cross-posting.

As plasma cutting is relatively new, I think this may be why I don't see much reference to plasma cutting in current Steel and Welding Codes.

I am wondering if there are any thoughts out there on how it would affect the long-term performance of such structures?

VoD

 

[SnTMan]

If you are talking of plasma cutting of plate into details for a welded assembly, the process is widely used in pressure vessels and, I am sure, many other industries as well. Pretty much exclusively used for stainless and non-ferrous metals that won't burn.

As with any thermal cutting process the cut edges would most likely need to be ground to sound metal before welding.

Regards,

Mike


The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

Whatever heat-affected zone caused by cutting that remains after cleaning the surface (see previous post) will be obliterated by the heat-affected zone caused by subsequent welding. I would have no concerns.
Actually plasma cutting and gouging has been around at least a quarter century. It is growing is use, if for no other reason than HSE.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[TimSchrader2]

If doing alot of parts Water jetting gives a much cleaner cut with much less kerf or jagged edges

 

[SnTMan]

Have had approx. 4" 304 plate cut both ways, waterjet much preferred

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[MikeHalloran]

Whatever heat-affected zone caused by cutting that remains after cleaning the surface (see previous post) will be obliterated by the heat-affected zone caused by subsequent welding. I would have no concerns.

I would have a lot of concern.

At a former employer, we had polished stainless sheet cut into the sinuous shapes needed for mitered elbows by means of a laser cutter. (For large J-shaped double walled exhaust pipes for gas turbine powered boats, very fast and very shiny.)

The welder who put the elbows together reported that the pieces fit nicely with no prep, but 'welded funny'.

He reported this AFTER our fussy customer rejected the assemblies because the welds were ugly.
They _were_ ugly.

Thereafter, we insisted that laser-cut edges must be ground back to remove the .005" of HAZ before welding.
Plasma cutting leaves an even larger HAZ and much rougher edges.

Waterjet cutting leaves no HAZ.
... but it does leave fine sand all over everything; someone has to wash the parts before welding.



Mike Halloran
Pembroke Pines, FL, USA

 

Mike,
I think I implied but did not explicitly state that this was after grinding the bevel surfaces to bright metal. Also I was thinking of more conventional welding processes which have significant base metal dilution.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[VoyageofDiscovery]

Thanks!